1. By Sam Rossoff

2. The Red Police Controlling High- Bandwidth Flows at the Congested Router By Ratul Mahajan Sally Floyd and David Wetherall

3. By Sam Rossoff Networking 101 ● Modern routers use a simple FIFO queue ● When a router runs out of room to store packets new packets are dropped from the end of the queue Internet | | | | | | | | | | | | | Router Destination

4. By Sam Rossoff Pushy Flows ● Because a router's bandwidth is fixed, if a single flow is very large it will hog up all the room on the queue ● Solution: Restrict the bandwidth of large flows

5. By Sam Rossoff Try Try Again ● Previous approaches break up into two categories ● Continuum: (SFQ, FIFO, etc) ● Scheduling: (CSFQ, FRED, RED, etc)

6. By Sam Rossoff Schedules and You ● CHOKe – Find a packet at random, compare to incoming packet and nuke both if same flow. – Limited performance: ● When there are too many high ● With high UDP flows ● CSFQ: Core Stateless Fair Queuing – Estimates packets fair share and drops based on rate estimate and fair share – Requires: ● Core “island” of routers ● Extra field in packet header

7. By Sam Rossoff The Design ● We really only need to worry about the big flows

8. By Sam Rossoff On Beyond Zebra ● This works because: – A Fraction of the flows make up most of the bandwidth – Predictable effect on the traffic going through the router

9. By Sam Rossoff The SEC Algorithm  Use the RED drop history  To identify flows that are sending more than ƒ ( r, p ), the reference TCP flow’s rate ( RTT r and packet drop rate p ). And thus dropping more than once in CL( r,p ) seconds.

10. By Sam Rossoff Epoch's are Fun  Congestion epoch length  Maintaining the packet drop history over K x CL ( R, p ) seconds  Partitioning the history into M lists  RED-PD identifies flows with losses in at least K of M lists  K = 3, M = 5, r = 40 ms and p = 1%

11. By Sam Rossoff But, Does it work? Flow 1:.1mbps Flow 2:.5 mbps Flow i: Rate(i-1) +.5mbps Identifying: g x f(R, p)

12. By Sam Rossoff I'm Going to Go with Yes ● RED-FD responds based on the drop rate. ● Few drops and flows run wild 1 CBR flow and 9 TCP flows The CBR flow starts with a rate of 0.25 Mbps, increases it to 4 Mbps at t=50s, and decreases it back to 0.25 Mbps at t=250s. The RTT of the TCP flows ranged from 30 to 70 ms.

13. By Sam Rossoff And Other Fun Facts on Cereal Boxes ● For flows identified as unresponsive, RED-PD increases the drop probability more quickly. ● Memory Required is only: ● RED-PD targets flows dropped from either itself, RED, or overflow ● Nets of these routers have faster response times and are more effecient.

14. By Sam Rossoff RED-PD Protects the Innocent ● Even works when there are a few flows of enormous bandwidth coming in. Flow 10: 5mbps Flow 11: 3mbps Flow 12: 1mbps

15. By Sam Rossoff Which is Why I Think I Would Make a Good President Now for my opponent who is a poopoo head